1. Field of the Invention
The present invention relates to an inhaler for ejecting medicine as micro-droplets and causing a user to inhale the medicine.
2. Description of the Related Art
There has been and still is a longstanding unmet demand for means for ejecting medicine as micro-droplets and administering the medicine to a user at his or her windpipe and lungs and a convenient method of causing medicine to be absorbed from lungs instead of subcutaneously injecting the medicine in order to make it easy for a user or a patient to administer medicine by him or herself. To meet the demand, inhalers designed to generate bubbles in medicine by means of a heater element arranged in an ejection head and eject medicine-containing-liquid under the pressure of the generated bubbles so as to eject the medicine as micro-droplets into the air flow to be inhaled by the patient via the patient's mouth have been developed (see International Publication Nos. WO95/01137 and WO02/04043).
If an ejection head for ejecting medicine is to be operated for a number of times and such an ejection head is exposed to air when it is not in use, dust can adhere to the ejection port(s) and the medicine disposed at and near the ejection port(s) contacts air and may coagulate to give rise to an undesirable situation.
Japanese Patent Application Laid-Open No. 2004-283244 discloses a cap that operates as a unit for protecting the medicine ejecting section of such an ejection head when the head is not in use.
An arrangement of providing a cap that can automatically be opened and closed as a unit for protecting the medicine ejecting section of an ejection head is also known (see Japanese Patent Application Laid-Open No. 2004-350976).
In such inhalers, an inhalation port by way of which a user inhales medicine is arranged at an end of the inhaler and connected to an air flow duct that leads medicine to the inhalation port by means of the air flow produced by the user trying to inhale medicine. The part of the inhaler where the ejected medicine passes can be cleaned if the inhalation port that is held in the user's mouth and the air flow duct for leading the ejected medicine to the inhalation port are removable. However, if the air flow duct is removable, the medicine ejecting section of the inhaler that is structurally located near the air flow duct can be damaged when removing the air flow duct and also when putting it back.
The cap for protecting the ejecting section as described above is designed to be opened and closed by a user. However, an operation of opening and closing such a cap is cumbersome to the user and the user can damage the ejecting section when he or she is opening or closing the cap. While such a cap can be realized as an automatic cap that is opened and closed automatically as described above, the ejecting section can be damaged if the air flow duct is removed by error when the cap is open. Thus, while Japanese Patent Applications Laid-Open Nos. 2004-283244 and 2004-350976 disclose protection caps as a unit for protecting the medicine ejecting section of an inhaler, they do not take the risk of damaging the medicine ejecting section in an operation of putting the removable air flow duct in position or taking the air flow duct out into consideration.